Initial import

third_party/duktape/duk_hthread_stacks.c

@@ -0,0 +1,407 @@
+/*
+ *  Thread stack (mainly call stack) primitives: allocation of activations,
+ *  unwinding catchers and activations, etc.
+ *
+ *  Value stack handling is a part of the API implementation.
+ */
+
+#include "third_party/duktape/duk_internal.h"
+
+/* Unwind the topmost catcher of the current activation (caller must check that
+ * both exist) without side effects.
+ */
+DUK_INTERNAL void duk_hthread_catcher_unwind_norz(duk_hthread *thr, duk_activation *act) {
+	duk_catcher *cat;
+
+	DUK_ASSERT(thr != NULL);
+	DUK_ASSERT(act != NULL);
+	DUK_ASSERT(act->cat != NULL);  /* caller must check */
+	cat = act->cat;
+	DUK_ASSERT(cat != NULL);
+
+	DUK_DDD(DUK_DDDPRINT("unwinding catch stack entry %p (lexenv check is done)", (void *) cat));
+
+	if (DUK_CAT_HAS_LEXENV_ACTIVE(cat)) {
+		duk_hobject *env;
+
+		env = act->lex_env;             /* current lex_env of the activation (created for catcher) */
+		DUK_ASSERT(env != NULL);        /* must be, since env was created when catcher was created */
+		act->lex_env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, env);  /* prototype is lex_env before catcher created */
+		DUK_HOBJECT_INCREF(thr, act->lex_env);
+		DUK_HOBJECT_DECREF_NORZ(thr, env);
+
+		/* There is no need to decref anything else than 'env': if 'env'
+		 * becomes unreachable, refzero will handle decref'ing its prototype.
+		 */
+	}
+
+	act->cat = cat->parent;
+	duk_hthread_catcher_free(thr, cat);
+}
+
+/* Same as above, but caller is certain no catcher-related lexenv may exist. */
+DUK_INTERNAL void duk_hthread_catcher_unwind_nolexenv_norz(duk_hthread *thr, duk_activation *act) {
+	duk_catcher *cat;
+
+	DUK_ASSERT(thr != NULL);
+	DUK_ASSERT(act != NULL);
+	DUK_ASSERT(act->cat != NULL);  /* caller must check */
+	cat = act->cat;
+	DUK_ASSERT(cat != NULL);
+
+	DUK_DDD(DUK_DDDPRINT("unwinding catch stack entry %p (lexenv check is not done)", (void *) cat));
+
+	DUK_ASSERT(!DUK_CAT_HAS_LEXENV_ACTIVE(cat));
+
+	act->cat = cat->parent;
+	duk_hthread_catcher_free(thr, cat);
+}
+
+DUK_LOCAL
+#if defined(DUK_USE_CACHE_CATCHER)
+DUK_NOINLINE
+#endif
+duk_catcher *duk__hthread_catcher_alloc_slow(duk_hthread *thr) {
+	duk_catcher *cat;
+
+	cat = (duk_catcher *) DUK_ALLOC_CHECKED(thr, sizeof(duk_catcher));
+	DUK_ASSERT(cat != NULL);
+	return cat;
+}
+
+#if defined(DUK_USE_CACHE_CATCHER)
+DUK_INTERNAL DUK_INLINE duk_catcher *duk_hthread_catcher_alloc(duk_hthread *thr) {
+	duk_catcher *cat;
+
+	DUK_ASSERT(thr != NULL);
+
+	cat = thr->heap->catcher_free;
+	if (DUK_LIKELY(cat != NULL)) {
+		thr->heap->catcher_free = cat->parent;
+		return cat;
+	}
+
+	return duk__hthread_catcher_alloc_slow(thr);
+}
+#else  /* DUK_USE_CACHE_CATCHER */
+DUK_INTERNAL duk_catcher *duk_hthread_catcher_alloc(duk_hthread *thr) {
+	return duk__hthread_catcher_alloc_slow(thr);
+}
+#endif  /* DUK_USE_CACHE_CATCHER */
+
+DUK_INTERNAL void duk_hthread_catcher_free(duk_hthread *thr, duk_catcher *cat) {
+	DUK_ASSERT(thr != NULL);
+	DUK_ASSERT(cat != NULL);
+
+#if defined(DUK_USE_CACHE_CATCHER)
+	/* Unconditional caching for now; freed in mark-and-sweep. */
+	cat->parent = thr->heap->catcher_free;
+	thr->heap->catcher_free = cat;
+#else
+	DUK_FREE_CHECKED(thr, (void *) cat);
+#endif
+}
+
+DUK_LOCAL
+#if defined(DUK_USE_CACHE_ACTIVATION)
+DUK_NOINLINE
+#endif
+duk_activation *duk__hthread_activation_alloc_slow(duk_hthread *thr) {
+	duk_activation *act;
+
+	act = (duk_activation *) DUK_ALLOC_CHECKED(thr, sizeof(duk_activation));
+	DUK_ASSERT(act != NULL);
+	return act;
+}
+
+#if defined(DUK_USE_CACHE_ACTIVATION)
+DUK_INTERNAL DUK_INLINE duk_activation *duk_hthread_activation_alloc(duk_hthread *thr) {
+	duk_activation *act;
+
+	DUK_ASSERT(thr != NULL);
+
+	act = thr->heap->activation_free;
+	if (DUK_LIKELY(act != NULL)) {
+		thr->heap->activation_free = act->parent;
+		return act;
+	}
+
+	return duk__hthread_activation_alloc_slow(thr);
+}
+#else  /* DUK_USE_CACHE_ACTIVATION */
+DUK_INTERNAL duk_activation *duk_hthread_activation_alloc(duk_hthread *thr) {
+	return duk__hthread_activation_alloc_slow(thr);
+}
+#endif  /* DUK_USE_CACHE_ACTIVATION */
+
+
+DUK_INTERNAL void duk_hthread_activation_free(duk_hthread *thr, duk_activation *act) {
+	DUK_ASSERT(thr != NULL);
+	DUK_ASSERT(act != NULL);
+
+#if defined(DUK_USE_CACHE_ACTIVATION)
+	/* Unconditional caching for now; freed in mark-and-sweep. */
+	act->parent = thr->heap->activation_free;
+	thr->heap->activation_free = act;
+#else
+	DUK_FREE_CHECKED(thr, (void *) act);
+#endif
+}
+
+/* Internal helper: process the unwind for the topmost activation of a thread,
+ * but leave the duk_activation in place for possible tailcall reuse.
+ */
+DUK_LOCAL void duk__activation_unwind_nofree_norz(duk_hthread *thr) {
+#if defined(DUK_USE_DEBUGGER_SUPPORT)
+	duk_heap *heap;
+#endif
+	duk_activation *act;
+	duk_hobject *func;
+	duk_hobject *tmp;
+
+	DUK_ASSERT(thr != NULL);
+	DUK_ASSERT(thr->callstack_curr != NULL);  /* caller must check */
+	DUK_ASSERT(thr->callstack_top > 0);
+	act = thr->callstack_curr;
+	DUK_ASSERT(act != NULL);
+	/* With lightfuncs, act 'func' may be NULL. */
+
+	/* With duk_activation records allocated separately, 'act' is a stable
+	 * pointer and not affected by side effects.
+	 */
+
+#if defined(DUK_USE_NONSTD_FUNC_CALLER_PROPERTY)
+	/*
+	 *  Restore 'caller' property for non-strict callee functions.
+	 */
+
+	func = DUK_ACT_GET_FUNC(act);
+	if (func != NULL && !DUK_HOBJECT_HAS_STRICT(func)) {
+		duk_tval *tv_caller;
+		duk_tval tv_tmp;
+		duk_hobject *h_tmp;
+
+		tv_caller = duk_hobject_find_entry_tval_ptr_stridx(thr->heap, func, DUK_STRIDX_CALLER);
+
+		/* The act->prev_caller should only be set if the entry for 'caller'
+		 * exists (as it is only set in that case, and the property is not
+		 * configurable), but handle all the cases anyway.
+		 */
+
+		if (tv_caller) {
+			DUK_TVAL_SET_TVAL(&tv_tmp, tv_caller);
+			if (act->prev_caller) {
+				/* Just transfer the refcount from act->prev_caller to tv_caller,
+				 * so no need for a refcount update.  This is the expected case.
+				 */
+				DUK_TVAL_SET_OBJECT(tv_caller, act->prev_caller);
+				act->prev_caller = NULL;
+			} else {
+				DUK_TVAL_SET_NULL(tv_caller);   /* no incref needed */
+				DUK_ASSERT(act->prev_caller == NULL);
+			}
+			DUK_TVAL_DECREF_NORZ(thr, &tv_tmp);
+		} else {
+			h_tmp = act->prev_caller;
+			if (h_tmp) {
+				act->prev_caller = NULL;
+				DUK_HOBJECT_DECREF_NORZ(thr, h_tmp);
+			}
+		}
+		DUK_ASSERT(act->prev_caller == NULL);
+	}
+#endif
+
+	/*
+	 *  Unwind debugger state.  If we unwind while stepping
+	 *  (for any step type), pause execution.  This is the
+	 *  only place explicitly handling a step out.
+	 */
+
+#if defined(DUK_USE_DEBUGGER_SUPPORT)
+	heap = thr->heap;
+	if (heap->dbg_pause_act == thr->callstack_curr) {
+		if (heap->dbg_pause_flags & DUK_PAUSE_FLAG_FUNC_EXIT) {
+			DUK_D(DUK_DPRINT("PAUSE TRIGGERED by function exit"));
+			duk_debug_set_paused(heap);
+		} else {
+			DUK_D(DUK_DPRINT("unwound past dbg_pause_act, set to NULL"));
+			heap->dbg_pause_act = NULL;  /* avoid stale pointers */
+		}
+		DUK_ASSERT(heap->dbg_pause_act == NULL);
+	}
+#endif
+
+	/*
+	 *  Unwind catchers.
+	 *
+	 *  Since there are no references in the catcher structure,
+	 *  unwinding is quite simple.  The only thing we need to
+	 *  look out for is popping a possible lexical environment
+	 *  established for an active catch clause.
+	 */
+
+	while (act->cat != NULL) {
+		duk_hthread_catcher_unwind_norz(thr, act);
+	}
+
+	/*
+	 *  Close environment record(s) if they exist.
+	 *
+	 *  Only variable environments are closed.  If lex_env != var_env, it
+	 *  cannot currently contain any register bound declarations.
+	 *
+	 *  Only environments created for a NEWENV function are closed.  If an
+	 *  environment is created for e.g. an eval call, it must not be closed.
+	 */
+
+	func = DUK_ACT_GET_FUNC(act);
+	if (func != NULL && !DUK_HOBJECT_HAS_NEWENV(func)) {
+		DUK_DDD(DUK_DDDPRINT("skip closing environments, envs not owned by this activation"));
+		goto skip_env_close;
+	}
+	/* func is NULL for lightfunc */
+
+	/* Catch sites are required to clean up their environments
+	 * in FINALLY part before propagating, so this should
+	 * always hold here.
+	 */
+	DUK_ASSERT(act->lex_env == act->var_env);
+
+	/* XXX: Closing the environment record copies values from registers
+	 * into the scope object.  It's side effect free as such, but may
+	 * currently run out of memory which causes an error throw.  This is
+	 * an actual sandboxing problem for error unwinds, and needs to be
+	 * fixed e.g. by preallocating the scope property slots.
+	 */
+	if (act->var_env != NULL) {
+		DUK_DDD(DUK_DDDPRINT("closing var_env record %p -> %!O",
+		                     (void *) act->var_env, (duk_heaphdr *) act->var_env));
+		duk_js_close_environment_record(thr, act->var_env);
+	}
+
+ skip_env_close:
+
+	/*
+	 *  Update preventcount
+	 */
+
+	if (act->flags & DUK_ACT_FLAG_PREVENT_YIELD) {
+		DUK_ASSERT(thr->callstack_preventcount >= 1);
+		thr->callstack_preventcount--;
+	}
+
+	/*
+	 *  Reference count updates, using NORZ macros so we don't
+	 *  need to handle side effects.
+	 *
+	 *  duk_activation pointers like act->var_env are intentionally
+	 *  left as garbage and not NULLed.  Without side effects they
+	 *  can't be used when the values are dangling/garbage.
+	 */
+
+	DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, act->var_env);
+	DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, act->lex_env);
+	tmp = DUK_ACT_GET_FUNC(act);
+	DUK_HOBJECT_DECREF_NORZ_ALLOWNULL(thr, tmp);
+	DUK_UNREF(tmp);
+}
+
+/* Unwind topmost duk_activation of a thread, caller must ensure that an
+ * activation exists.  The call is side effect free, except that scope
+ * closure may currently throw an out-of-memory error.
+ */
+DUK_INTERNAL void duk_hthread_activation_unwind_norz(duk_hthread *thr) {
+	duk_activation *act;
+
+	duk__activation_unwind_nofree_norz(thr);
+
+	DUK_ASSERT(thr->callstack_curr != NULL);
+	DUK_ASSERT(thr->callstack_top > 0);
+	act = thr->callstack_curr;
+	thr->callstack_curr = act->parent;
+	thr->callstack_top--;
+
+	/* Ideally we'd restore value stack reserve here to caller's value.
+	 * This doesn't work for current unwind call sites however, because
+	 * the current (unwound) value stack top may be above the reserve.
+	 * Thus value stack reserve is restored by the call sites.
+	 */
+
+	/* XXX: inline for performance builds? */
+	duk_hthread_activation_free(thr, act);
+
+	/* We could clear the book-keeping variables like retval_byteoff for
+	 * the topmost activation, but don't do so now as it's not necessary.
+	 */
+}
+
+DUK_INTERNAL void duk_hthread_activation_unwind_reuse_norz(duk_hthread *thr) {
+	duk__activation_unwind_nofree_norz(thr);
+}
+
+/* Get duk_activation for given callstack level or NULL if level is invalid
+ * or deeper than the call stack.  Level -1 refers to current activation, -2
+ * to its caller, etc.  Starting from Duktape 2.2 finding the activation is
+ * a linked list scan which gets more expensive the deeper the lookup is.
+ */
+DUK_INTERNAL duk_activation *duk_hthread_get_activation_for_level(duk_hthread *thr, duk_int_t level) {
+	duk_activation *act;
+
+	if (level >= 0) {
+		return NULL;
+	}
+	act = thr->callstack_curr;
+	for (;;) {
+		if (act == NULL) {
+			return act;
+		}
+		if (level == -1) {
+			return act;
+		}
+		level++;
+		act = act->parent;
+	}
+	/* never here */
+}
+
+#if defined(DUK_USE_FINALIZER_TORTURE)
+DUK_INTERNAL void duk_hthread_valstack_torture_realloc(duk_hthread *thr) {
+	duk_size_t alloc_size;
+	duk_tval *new_ptr;
+	duk_ptrdiff_t alloc_end_off;
+	duk_ptrdiff_t end_off;
+	duk_ptrdiff_t bottom_off;
+	duk_ptrdiff_t top_off;
+
+	if (thr->valstack == NULL) {
+		DUK_D(DUK_DPRINT("skip valstack torture realloc, valstack is NULL"));
+		return;
+	}
+
+	alloc_end_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_alloc_end - (duk_uint8_t *) thr->valstack);
+	end_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_end - (duk_uint8_t *) thr->valstack);
+	bottom_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_bottom - (duk_uint8_t *) thr->valstack);
+	top_off = (duk_ptrdiff_t) ((duk_uint8_t *) thr->valstack_top - (duk_uint8_t *) thr->valstack);
+	alloc_size = (duk_size_t) alloc_end_off;
+	if (alloc_size == 0) {
+		DUK_D(DUK_DPRINT("skip valstack torture realloc, alloc_size is zero"));
+		return;
+	}
+
+	/* Use DUK_ALLOC_RAW() to avoid side effects. */
+	new_ptr = (duk_tval *) DUK_ALLOC_RAW(thr->heap, alloc_size);
+	if (new_ptr != NULL) {
+		duk_memcpy((void *) new_ptr, (const void *) thr->valstack, alloc_size);
+		duk_memset((void *) thr->valstack, 0x55, alloc_size);
+		DUK_FREE_CHECKED(thr, (void *) thr->valstack);
+		thr->valstack = new_ptr;
+		thr->valstack_alloc_end = (duk_tval *) ((duk_uint8_t *) new_ptr + alloc_end_off);
+		thr->valstack_end = (duk_tval *) ((duk_uint8_t *) new_ptr + end_off);
+		thr->valstack_bottom = (duk_tval *) ((duk_uint8_t *) new_ptr + bottom_off);
+		thr->valstack_top = (duk_tval *) ((duk_uint8_t *) new_ptr + top_off);
+	} else {
+		DUK_D(DUK_DPRINT("failed to realloc valstack for torture, ignore"));
+	}
+}
+#endif  /* DUK_USE_FINALIZER_TORTURE */